// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef UI_APP_LIST_APP_LIST_MODEL_H_
#define UI_APP_LIST_APP_LIST_MODEL_H_

#include <stddef.h>

#include <string>
#include <vector>

#include "base/macros.h"
#include "base/memory/scoped_ptr.h"
#include "base/observer_list.h"
#include "ui/app_list/app_list_export.h"
#include "ui/app_list/app_list_item_list.h"
#include "ui/app_list/app_list_item_list_observer.h"
#include "ui/app_list/search_result.h"
#include "ui/base/models/list_model.h"

namespace app_list {

class AppListFolderItem;
class AppListItem;
class AppListItemList;
class AppListModelObserver;
class SearchBoxModel;

// Master model of app list that consists of three sub models: AppListItemList,
// SearchBoxModel and SearchResults. The AppListItemList sub model owns a list
// of AppListItems and is displayed in the grid view. SearchBoxModel is
// the model for SearchBoxView. SearchResults owns a list of SearchResult.
// NOTE: Currently this class observes |top_level_item_list_|. The View code may
// move entries in the item list directly (but can not add or remove them) and
// the model needs to notify its observers when this occurs.
class APP_LIST_EXPORT AppListModel : public AppListItemListObserver {
public:
    enum Status {
        STATUS_NORMAL,
        STATUS_SYNCING, // Syncing apps or installing synced apps.
    };

    // Do not change the order of these as they are used for metrics.
    enum State {
        STATE_APPS = 0,
        STATE_SEARCH_RESULTS,
        STATE_START,
        STATE_CUSTOM_LAUNCHER_PAGE,
        // Add new values here.

        INVALID_STATE,
        STATE_LAST = INVALID_STATE,
    };

    typedef ui::ListModel<SearchResult> SearchResults;

    AppListModel();
    ~AppListModel() override;

    void AddObserver(AppListModelObserver* observer);
    void RemoveObserver(AppListModelObserver* observer);

    void SetStatus(Status status);

    void SetState(State state);
    State state() { return state_; }

    // Finds the item matching |id|.
    AppListItem* FindItem(const std::string& id);

    // Find a folder item matching |id|.
    AppListFolderItem* FindFolderItem(const std::string& id);

    // Adds |item| to the model. The model takes ownership of |item|. Returns a
    // pointer to the item that is safe to use (e.g. after passing ownership).
    AppListItem* AddItem(scoped_ptr<AppListItem> item);

    // Adds |item| to an existing folder or creates a new folder. If |folder_id|
    // is empty, adds the item to the top level model instead. The model takes
    // ownership of |item|. Returns a pointer to the item that is safe to use.
    AppListItem* AddItemToFolder(scoped_ptr<AppListItem> item,
        const std::string& folder_id);

    // Merges two items. If the target item is a folder, the source item is added
    // to the end of the target folder. Otherwise a new folder is created in the
    // same position as the target item with the target item as the first item in
    // the new folder and the source item as the second item. Returns the id of
    // the target folder, or an empty string if the merge failed. The source item
    // may already be in a folder. See also the comment for RemoveItemFromFolder.
    // NOTE: This should only be called by the View code (not the sync code); it
    // enforces folder restrictions (e.g. the target can not be an OEM folder).
    const std::string MergeItems(const std::string& target_item_id,
        const std::string& source_item_id);

    // Move |item| to the folder matching |folder_id| or to the top level if
    // |folder_id| is empty. |item|->position will determine where the item
    // is positioned. See also the comment for RemoveItemFromFolder.
    void MoveItemToFolder(AppListItem* item, const std::string& folder_id);

    // Move |item| to the folder matching |folder_id| or to the top level if
    // |folder_id| is empty. The item will be inserted before |position| or at
    // the end of the list if |position| is invalid. Note: |position| is copied
    // in case it refers to the containing folder which may get deleted. See also
    // the comment for RemoveItemFromFolder. Returns true if the item was moved.
    // NOTE: This should only be called by the View code (not the sync code); it
    // enforces folder restrictions (e.g. the source folder can not be type OEM).
    bool MoveItemToFolderAt(AppListItem* item,
        const std::string& folder_id,
        syncer::StringOrdinal position);

    // Sets the position of |item| either in |top_level_item_list_| or the folder
    // specified by |item|->folder_id(). If |new_position| is invalid, move the
    // item to the end of the list.
    void SetItemPosition(AppListItem* item,
        const syncer::StringOrdinal& new_position);

    // Sets the name of |item| and notifies observers.
    void SetItemName(AppListItem* item, const std::string& name);

    // Sets the name and short name of |item| and notifies observers.
    void SetItemNameAndShortName(AppListItem* item,
        const std::string& name,
        const std::string& short_name);

    // Deletes the item matching |id| from |top_level_item_list_| or from the
    // appropriate folder.
    void DeleteItem(const std::string& id);

    // Wrapper around DeleteItem() which will also clean up if its parent folder
    // has a single child left.
    void DeleteUninstalledItem(const std::string& id);

    // Call OnExtensionPreferenceChanged() for all items in the model.
    void NotifyExtensionPreferenceChanged();

    // Sets whether or not the folder UI should be enabled. If |folders_enabled|
    // is false, removes any non-OEM folders.
    void SetFoldersEnabled(bool folders_enabled);

    // Sets whether or not the custom launcher page should be enabled.
    void SetCustomLauncherPageEnabled(bool enabled);
    bool custom_launcher_page_enabled() const
    {
        return custom_launcher_page_enabled_;
    }

    void set_custom_launcher_page_name(const std::string& name)
    {
        custom_launcher_page_name_ = name;
    }

    const std::string& custom_launcher_page_name() const
    {
        return custom_launcher_page_name_;
    }

    // Pushes a custom launcher page's subpage into the state stack in the model.
    void PushCustomLauncherPageSubpage();

    // If the state stack is not empty, pops a subpage from the stack and returns
    // true. Returns false if the stack was empty.
    bool PopCustomLauncherPageSubpage();

    // Clears the custom launcher page's subpage state stack from the model.
    void ClearCustomLauncherPageSubpages();

    int custom_launcher_page_subpage_depth()
    {
        return custom_launcher_page_subpage_depth_;
    }

    void SetSearchEngineIsGoogle(bool is_google);
    bool search_engine_is_google() const { return search_engine_is_google_; }

    // Filters the given |results| by |display_type|. The returned list is
    // truncated to |max_results|.
    static std::vector<SearchResult*> FilterSearchResultsByDisplayType(
        SearchResults* results,
        SearchResult::DisplayType display_type,
        size_t max_results);

    AppListItemList* top_level_item_list() { return top_level_item_list_.get(); }

    SearchBoxModel* search_box() { return search_box_.get(); }
    SearchResults* results() { return results_.get(); }
    Status status() const { return status_; }
    bool folders_enabled() const { return folders_enabled_; }

private:
    // AppListItemListObserver
    void OnListItemMoved(size_t from_index,
        size_t to_index,
        AppListItem* item) override;

    // Returns an existing folder matching |folder_id| or creates a new folder.
    AppListFolderItem* FindOrCreateFolderItem(const std::string& folder_id);

    // Adds |item_ptr| to |top_level_item_list_| and notifies observers.
    AppListItem* AddItemToItemListAndNotify(
        scoped_ptr<AppListItem> item_ptr);

    // Adds |item_ptr| to |top_level_item_list_| and notifies observers that an
    // Update occured (e.g. item moved from a folder).
    AppListItem* AddItemToItemListAndNotifyUpdate(
        scoped_ptr<AppListItem> item_ptr);

    // Adds |item_ptr| to |folder| and notifies observers.
    AppListItem* AddItemToFolderItemAndNotify(AppListFolderItem* folder,
        scoped_ptr<AppListItem> item_ptr);

    // Removes |item| from |top_level_item_list_| or calls RemoveItemFromFolder if
    // |item|->folder_id is set.
    scoped_ptr<AppListItem> RemoveItem(AppListItem* item);

    // Removes |item| from |folder|. If |folder| becomes empty, deletes |folder|
    // from |top_level_item_list_|. Does NOT trigger observers, calling function
    // must do so.
    scoped_ptr<AppListItem> RemoveItemFromFolder(AppListFolderItem* folder,
        AppListItem* item);

    scoped_ptr<AppListItemList> top_level_item_list_;

    scoped_ptr<SearchBoxModel> search_box_;
    scoped_ptr<SearchResults> results_;

    Status status_;
    State state_;
    base::ObserverList<AppListModelObserver, true> observers_;
    bool folders_enabled_;
    bool custom_launcher_page_enabled_;
    std::string custom_launcher_page_name_;
    bool search_engine_is_google_;

    // The current number of subpages the custom launcher page has pushed.
    int custom_launcher_page_subpage_depth_;

    DISALLOW_COPY_AND_ASSIGN(AppListModel);
};

} // namespace app_list

#endif // UI_APP_LIST_APP_LIST_MODEL_H_
